Joint implants having porous structures formed utilizing additive manufacturing and related systems and methods

ABSTRACT

A medical implant which comprises a porous lattice is fabricated with additive manufacturing techniques such as direct metal laser sintering. A CAD model of the porous lattice is created by defining a trimming volume and merging some lattice elements with adjacent solid substrate.

RELATED APPLICATIONS

This application is a continuation of, and claims priority to,International Patent Application No. PCT/US20/24710, filed on Mar. 25,2020. The contents of the aforementioned priority application are herebyincorporated by reference in their entireties.

BACKGROUND

The present disclosure relates generally to biomedical implants, andmore specifically to methods and apparatuses directed to additivemanufacturing of porous structures for such biomedical implants.

Traditionally, the manufacture of biomedical implants has incorporatedthe application of spray-on or roughened porous materials or layers topre-formed biomedical implants to facilitate attachment and ingrowth oftissues to the implants. More recently, the manufacture of biomedicalimplants have alternatively or additionally utilized additivemanufacturing techniques, also referred to as 3-dimensional printing, togenerate porous structures for biomedical implants.

Embodiments described herein improve upon existing additivemanufacturing techniques for generating porous structures.

It should be noted that this Background is not intended to be an aid indetermining the scope of the claimed subject matter nor be viewed aslimiting the claimed subject matter to implementations that solve any orall of the disadvantages or problems presented above. The discussion ofany technology, documents, or references in this Background sectionshould not be interpreted as an admission that the material described isprior art to any of the subject matter claimed herein.

SUMMARY

It is understood that various configurations of the subject technologywill become apparent to those skilled in the art from the disclosure,wherein various configurations of the subject technology are shown anddescribed by way of illustration. As will be realized, the subjecttechnology is capable of other and different configurations and itsseveral details are capable of modification in various other respects,all without departing from the scope of the subject technology.Accordingly, the summary, drawings and detailed description are to beregarded as illustrative in nature and not as restrictive.

A method for fabricating an implant device comprising a porous latticeis provided. The method includes creating, by a computing device, amodel of the implant device comprising the porous lattice. The creatingincludes defining an initial lattice volume having a bounding surfacefor the implant device. The creating includes populating the initiallattice volume with a plurality of seed points. The creating includespopulating the initial lattice volume with a plurality of nodes andstruts that divide the initial lattice volume into a plurality of3-dimensional regions, thereby defining an initial lattice. The creatingincludes defining a second volume within the initial lattice volume suchthat a trimming boundary is defined between the initial lattice volumeand the second volume. The creating includes removing struts and nodes,and portions thereof from the model that are located outside thetrimming boundary. The creating includes fabricating the implant devicecomprising the porous lattice at least in part by exposing fusiblematerial to a heating source according to the model.

Another method for fabricating an implant device comprising a porouslattice is provided. The method includes creating, by a computingdevice, a model of the implant device comprising the porous lattice. Thecreating includes defining an initial lattice volume having a boundingsurface for the implant device. The creating includes populating theinitial lattice volume with a plurality of seed points. The creatingincludes populating the initial lattice volume with a plurality of nodesand struts that connect the nodes to divide the initial lattice volumeinto a plurality of 3-dimensional regions, thereby defining an initiallattice. The creating includes attracting one or more nodes and/orstruts toward a substrate of the implant device such that at least oneattracted node or strut is positioned coincident with or at least partlywithin the substrate of the implant device. The creating includesmerging some or all of the attracted nodes and/or struts with thesubstrate of the implant device.

Yet another method for fabricating an implant device comprising a porouslattice is provided. The method includes creating, by a computingdevice, a model of the implant device comprising the porous lattice. Thecreating includes defining an initial lattice volume having a boundingsurface for the implant device. The creating includes populating theinitial lattice volume with a plurality of seed points. The creatingincludes populating the initial lattice volume with a plurality of nodesand struts that divide the initial lattice volume into a plurality of3-dimensional regions, thereby defining an initial lattice. The creatingincludes defining a second volume within the initial lattice volume suchthat a trimming boundary is defined between the initial lattice volumeand the second volume. The creating includes removing struts and nodes,and portions thereof from the model that are located outside thetrimming boundary.

An implant device made by any method(s) described herein are alsoprovided.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are discussed in detail in conjunction with theFigures described below, with an emphasis on highlighting theadvantageous features. These embodiments are for illustrative purposesonly and any scale that may be illustrated therein does not limit thescope of the technology disclosed. These drawings include the followingfigures, in which like numerals indicate like parts.

FIG. 1 illustrates a bone-facing side of a patellar implant, asfabricated with additive manufacturing, according to some embodiments;

FIG. 2A illustrates a CAD model of a porous lattice comprising strutsintegrated with a periphery of an implant, according to someembodiments;

FIG. 2B illustrates the porous lattice of FIG. 2A, as fabricated withadditive manufacturing, according to some embodiments;

FIG. 3 illustrates a CAD model of an initial volume for containing aporous lattice of an implant substrate, according to some embodiments;

FIG. 4 illustrates a CAD model of the volume of FIG. 3 containing aplurality of nodes and struts forming the porous lattice, according tosome embodiments;

FIG. 5 illustrates a CAD model comprising a plurality of strutsextending along an outer boundary of the initial volume of FIG. 4 ,according to some embodiments;

FIG. 6 illustrates a CAD model of the initial volume of FIG. 5 trimmedto exclude at least some of the plurality of nodes and struts extendingalong the outer boundary of the initial volume, according to someembodiments;

FIG. 7 illustrates a CAD model of a trimmed porous lattice, according tosome embodiments;

FIG. 8 illustrates a CAD model of the trimmed lattice of FIG. 7 havingone or more struts and/or nodes proximate to the implant substrate,attracted to the implant substrate, according to some embodiments;

FIG. 9 illustrates a CAD model of the trimmed volume of FIG. 8 havingthe one or more attracted struts and nodes merged with the implantsubstrate, according to some embodiments;

FIG. 10 illustrates a computing device configured to generate a CADmodel of an implant comprising a conformal, porous lattice, according tosome embodiments;

FIG. 11 illustrates an additive manufacturing device configured tofabricate an implant device comprising a porous lattice based on atleast one CAD model, according to some embodiments;

FIG. 12 illustrates a flowchart of a method for fabricating an implantdevice comprising a conformal, porous lattice, according to someembodiments.

DETAILED DESCRIPTION

The following description and examples illustrate some exemplaryimplementations, embodiments, and arrangements of the disclosedinvention in detail. Those of skill in the art will recognize that thereare numerous variations and modifications of this invention that areencompassed by its scope. Accordingly, the description of a certainexample embodiment should not be deemed to limit the scope of thepresent invention.

Implementations of the technology described herein are directedgenerally to implants for use in joint arthroplasty and morespecifically to methods and apparatuses directed to additivemanufacturing of implants, for example patellar implants, utilizingdirect metal laser sintering (DMLS), for use in cementless total kneearthroplasty.

General Interpretive Principles for the Present Disclosure

Various aspects of the novel systems, apparatuses, and methods aredescribed more fully herein with reference to the accompanying drawings.The teachings disclosure may, however, be embodied in many differentforms and should not be construed as limited to any specific structureor function presented throughout this disclosure. Rather, these aspectsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the disclosure to those skilled in theart. Based on the teachings herein one skilled in the art shouldappreciate that the scope of the disclosure is intended to cover anyaspect of the novel systems, apparatuses, and methods disclosed herein,whether implemented independently of or combined with any other aspectof the disclosure. For example, a system or an apparatus may beimplemented, or a method may be practiced using any one or more of theaspects set forth herein. In addition, the scope of the disclosure isintended to cover such a system, apparatus or method which is practicedusing other structure, functionality, or structure and functionality inaddition to or other than the various aspects of the disclosure setforth herein. It should be understood that any aspect disclosed hereinmay be set forth in one or more elements of a claim. Although somebenefits and advantages of the preferred aspects are mentioned, thescope of the disclosure is not intended to be limited to particularbenefits, uses, or objectives. The detailed description and drawings aremerely illustrative of the disclosure rather than limiting, the scope ofthe disclosure being defined by the appended claims and equivalentsthereof.

With respect to the use of plural vs. singular terms herein, thosehaving skill in the art can translate from the plural to the singularand/or from the singular to the plural as is appropriate to the contextand/or application. The various singular/plural permutations may beexpressly set forth herein for sake of clarity.

When describing an absolute value of a characteristic or property of athing or act described herein, the terms “substantial,” “substantially,”“essentially,” “approximately,” and/or other terms or phrases of degreemay be used without the specific recitation of a numerical range. Whenapplied to a characteristic or property of a thing or act describedherein, these terms refer to a range of the characteristic or propertythat is consistent with providing a desired function associated withthat characteristic or property.

In those cases where a single numerical value is given for acharacteristic or property, it is intended to be interpreted as at leastcovering deviations of that value within one significant digit of thenumerical value given.

If a numerical value or range of numerical values is provided to definea characteristic or property of a thing or act described herein, whetheror not the value or range is qualified with a term of degree, a specificmethod of measuring the characteristic or property may be defined hereinas well. In the event no specific method of measuring the characteristicor property is defined herein, and there are different generallyaccepted methods of measurement for the characteristic or property, thenthe measurement method should be interpreted as the method ofmeasurement that would most likely be adopted by one of ordinary skillin the art given the description and context of the characteristic orproperty. In the further event there is more than one method ofmeasurement that is equally likely to be adopted by one of ordinaryskill in the art to measure the characteristic or property, the value orrange of values should be interpreted as being met regardless of whichmethod of measurement is chosen.

It will be understood by those within the art that terms used herein,and especially in the appended claims (e.g., bodies of the appendedclaims) are intended as “open” terms unless specifically indicatedotherwise (e.g., the term “including” should be interpreted as“including but not limited to,” the term “having” should be interpretedas “having at least,” the term “includes” should be interpreted as“includes but is not limited to,” etc.).

It will be further understood by those within the art that if a specificnumber of an introduced claim recitation is intended, such an intentwill be explicitly recited in the claim, and in the absence of suchrecitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations).

In those instances where a convention analogous to “at least one of A,B, and C” is used, such a construction would include systems that have Aalone, B alone, C alone, A and B together without C, A and C togetherwithout B, B and C together without A, as well as A, B, and C together.It will be further understood by those within the art that virtually anydisjunctive word and/or phrase presenting two or more alternative terms,whether in the description, claims, or drawings, should be understood tocontemplate the possibilities of including one of the terms, either ofthe terms, or both terms. For example, the phrase “A or B” will beunderstood to include A without B, B without A, as well as A and Btogether.”

Various modifications to the implementations described in thisdisclosure can be readily apparent to those skilled in the art, andgeneric principles defined herein can be applied to otherimplementations without departing from the spirit or scope of thisdisclosure. Thus, the disclosure is not intended to be limited to theimplementations shown herein but is to be accorded the widest scopeconsistent with the claims, the principles and the novel featuresdisclosed herein. The word “exemplary” is used exclusively herein tomean “serving as an example, instance, or illustration.” Anyimplementation described herein as “exemplary” is not necessarily to beconstrued as preferred or advantageous over other implementations.

Certain features that are described in this specification in the contextof separate implementations also can be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation also can be implemented inmultiple implementations separately or in any suitable sub-combination.Moreover, although features can be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination can be directed to asub-combination or variation of a sub-combination.

Discussion of Several Exemplary Embodiments of the Present Disclosure

Initial discussion of an example implant fabricated in accordance withthis disclosure will be described in connection with FIGS. 1-2B. Exampletechniques for fabricating such implants will then be described in moredetail in connection with FIGS. 3-12 . The specific example described indetail herein is a patellar implant, but the design and fabricationmethods and systems described herein could be applied to any implantwhere a porous structure is desirable.

FIG. 1 illustrates a bone-facing side 110 of a patellar implant 102,including a porous lattice 114, as fabricated with additivemanufacturing, according to some embodiments. In some embodiments,patellar implant 102 can comprise a solid titanium alloy substrate, forexample Ti-6Al-4V. However, the present application is not so limitedand patellar implant 102 can additionally or alternatively comprise anysuitable metal, alloy, polymer or other material. Bone-facing side 110of patellar implant 102 can comprise one or more posts 112 a, 112 b, 112c (112 a-112 c) configured to anchor bone, for example the patella, ofthe patient to patellar implant 102. During a healing process subsequentto implantation, the patient's bone may adhere to bone-facing side 110of patellar implant 102, including to posts 112 a-112 c, therebyanchoring patellar implant 102 in place. Porous lattice 114 can comprisegenerally linearly extending struts that meet at nodes. Node and strutposition may be a randomized or pseudo-randomized structure, for examplebased on a 3-dimensional Voronoi tessellation and may be fabricated in asingle step utilizing additive manufacturing techniques, as will bedescribed in more detail below. While not illustrated in FIG. 1 ,patellar implant 102 also comprises a joint-facing, or articulating,side opposite bone-facing side 110 that is substantially contouredappropriately for abutting the knee joint of a patient.

FIG. 2A illustrates a magnified CAD model of porous lattice 114 asintegrated with patellar implant 102, according to some embodiments. Aspreviously described, porous lattice 114 can comprise a randomized orpseudo-randomized structure based on a 3-dimensional Voronoitessellation, which can produce a Gaussian distribution of porediameters centered around a desired mean pore diameter while maintaininga desired level of overall porosity to facilitate bone in-growth andimplant securement during the healing process. Porous lattice 114 maycomprise a plurality of open ended (e.g., cantilevered from a node),struts 302 at its exterior, bone-facing surface to increase surfaceroughness and initial bone in-growth and fixation. Porous lattice 114may further comprise a plurality of struts 304 that integrate with edgefeatures 306 of the solid substrate of patellar implant 102 to ensuresufficient mechanical support and to provide a robust connection betweenporous lattice 114 and the solid substrate of patellar implant 102. FIG.2B illustrates a magnified view of porous lattice 114, as actuallyfabricated, according to some embodiments.

Although FIGS. 2A and 2B illustrate the plurality of struts 304integrating with edge features 306 of patellar implant 102 at posts 112a-c, the present disclosure is not so limited and the plurality ofstruts 304 can also integrate with edge features of patellar implant 102along substantially all surfaces of patellar implant that abut porouslattice 114, for example at least a portion of bone-facing surface 110of patellar implant 102 and/or at least portions of top surfaces ofposts 112 a-c (see, e.g., FIG. 1 ).

An example process for generating a CAD model of porous lattice 114integrated with patellar implant 102 and their subsequent fabricationwill now be described in more detail in connection with FIGS. 3-12 .

FIG. 3 illustrates a CAD model of an initial volume 402 intended tocontain porous lattice 114 of patellar implant 102, according to someembodiments. Initial volume 402 and the solid substrate of patellarimplant 102 can be designed using standard CAD techniques includinglattice-modeling computer software, for example Element by nTopology ofNew York, N.Y. and/or Autodesk Within Medical by Autodesk of San Rafael,Calif. Although initial volume 402 is illustrated as having asubstantially cylindrical shape and an outer boundary that curves tosubstantially match the slope of patellar implant 102 at the abuttingedge features of post 112 c, the present disclosure is not so limitedand initial volume 402 may have any suitable shape defined by anysuitable outer boundary.

Initial volume 402 can be populated with a plurality of seed points. The3-dimensional distribution of at least some of these seed points can berandom or pseudo-random and can be performed repeatably on identicalvolumes, for example similar volumes surrounding the remaining posts 112a, 112 b. In some embodiments, the distribution of these seed points canbe based on a Poisson-disc sampling strategy, for example as describedby Gamito M N, Maddock S C, Accurate Multi-dimensional Poisson-discSampling, ACM Transactions on Graphics (2009) 29, 1, Article 8 (December2009), which is hereby incorporated by reference in its entirety. UsingPoisson-disc sampling allows for specification of seed points that willresult in a desired target cell size when a Voronoi tessellation issubsequently applied to sub-divide initial lattice volume 402.

FIG. 4 illustrates a CAD model of initial volume 402 subdivided into aplurality of 3-dimensional regions by a plurality of struts 502. Asnoted above, in some implementations, positions of struts and nodes maybe defined according to a Voronoi tessellation. As shown in FIG. 4 , aVoronoi tessellation may be utilized to define a plurality of nodesconnected by a plurality of struts 502, subdividing initial volume 402into a plurality of 3-dimensional regions.

The generalized n-dimensional Voronoi tessellation technique was definedby Voronoi, Georges in the early 20th century. (See for example,“Nouvelles applications des parametres continus a la theorie des formsquadratiques.” Premier Memoire. Sur quelques proprietes des formsquadratiques positives parfaits.” Journal fur die reine und angewandteMathematik 133 (1908): 97-178; Voronoi, Georges, and “Nouvellesapplications des parametres continus a la theorie des formsquadratiques. Deuxieme Memoire. Recherches sur les parallelloedresprimitifs.” Journal fur die reine und angewandte Mathematik 134 (1908):198-287; 136 (1909): 67-181. Example algorithmic implementations ofVoronoi tessellation are described in Guibas, et al., “Randomizedincremental construction of Delaunay and Voronoi diagrams,” Algorithmica(1992) 7:381-413, which is hereby incorporated by reference in itsentirety.

The resulting lattice 500 comprises a plurality of struts 502 thatextend along the mating boundaries of adjacent subdivided 3-dimensionalregions of initial volume 402, and a plurality of nodes 504 which definepositions where struts 502 intersect with one another. Strut and nodelocations may be defined by the locations of the plurality of seedpoints used by the Voronoi tessellation.

The distribution of seed points may be made to have some non-random ornon-pseudo-random characteristics. For example, the sampling strategyemployed to generate seed point location (such as various strategiesdescribed in Gamito, as previously described) can be biased to have ahigher point density in some regions of the lattice than others. Thiscould be done to improve lattice characteristics by, for example,generating an increasing density of seed points from the outer boundaryof the lattice to the inner boundary of the lattice. This can increaselattice mechanical strength without significantly degrading bonein-growth properties of the lattice. Of course, even within a randomdistribution of points, different regions can be defined that havevarying point density, and as noted above, there still can beconsiderable randomness in the point positioning in local regions. Inthis case, a different point density in one region than another means apoint density difference not reasonably producible by a random orpseudo-random process alone.

FIG. 5 illustrates a CAD model showing the plurality of struts 502 thatextend along an outer boundary of initial volume 402, according to someembodiments. To increase the surface roughness of lattice 500, atrimming volume may be defined that is partly or wholly on the interiorof initial volume 402. At least some struts 502 that conform to thebone-facing outer boundary of initial volume 402 are outside thetrimming volume, and at least some struts extend through the surface ofthe trimming volume out to the surface of the initial volume 402.Portions of lattice 500 within the trimming volume may be kept in themodel, while portions of lattice 500 within initial volume 402 but notwithin the trimming volume may be removed from the model. Accordingly,an outer layer between the outer surface of the initial volume 402 andthe outer surface of the trimming volume may be trimmed away by removingfrom the model struts and nodes outside the trimming volume. Struts ofthe model that intersect the surface of the trimming volume may beterminated at or near the point of intersection, producing an outersurface of open-ended struts with free strut ends as mentioned above.

An example of the result of such lattice trimming is shown in FIG. 6 ,which illustrates a CAD model of a trimmed lattice 702 where the modelhas been modified by eliminating at least portions of the plurality ofstruts 502 outside the trimming boundary. In some implementations, thefree struts may be manipulated after trimming by having their initialend position and/or orientation with respect to the trimming volumeboundary. This can improve manufacturability of the lattice or modifyphysical properties of the lattice such as strength or coefficient offriction. For example, a group of free strut ends may be extendedfurther outward from the trimming volume boundary than the remainingfree strut ends. The group may be selected as a randomly orpseudo-randomly selected subset of free strut ends that numbers somepercentage of the total number of free strut ends. The angle oforientation of the struts with free ends with respect to the trimmingvolume boundary can also be manipulated. For example, the angle from thesurface normal can be contained within a particular range. Any strutswith free strut ends outside this angle could be rotated toward thenormal vector at the boundary intersection point to be at an angle fromthe normal that is somewhere within the normal range. Thisre-orientation could be randomized or pseudo-randomized. For example,for each strut that is outside the desired angular range and thusrequires re-orientation, a random or pseudo-random angle within thedesired range could be selected, and each strut could be re-oriented tobe at the angle from normal selected for that strut. It will beappreciated that both of the above described free strut manipulationscould be performed on the same trimmed lattice structure such that someor all free strut ends are changed in both length and orientation.

To further improve integration of trimmed lattice 702 with the solidsubstrate of patellar implant 102, at least some of the nodes of trimmedlattice 702 immediately adjacent to the solid substrate of patellarimplant 102, and the associated struts, are attracted to the solidsubstrate of patellar implant 102 such that the attracted nodes and atleast portions of the associated struts are positioned within the modelboundary of the solid substrate of patellar implant 102. For example,FIG. 7 illustrates a CAD model of trimmed lattice 702 substantiallysimilar to FIG. 6 , however, further visually indicating a boundary 802of trimmed lattice volume 702 on the solid substrate of patellar implant102. FIG. 8 illustrates a CAD model of trimmed lattice 702 having one ormore nodes and associated struts 902, immediately adjacent to the solidsubstrate of patellar implant 102, attracted to the solid substrate ofpatellar implant 102. FIG. 8 further illustrates bone-facing side 110 ofpatellar implant 102 as translucent for ease of visualization of theattraction step. FIG. 9 illustrates a CAD model of trimmed lattice 702having the one or more attracted nodes and associated struts 902 mergedwith the solid substrate of patellar implant 102.

Once the attracted nodes and struts of trimmed lattice 702 have beenmerged with the solid substrate of patellar implant 102, all or aportion of struts 502 can be thickened to a suitable and/or desiredthickness and/or cross-sectional geometry, for example a substantiallycircular cross-sectional geometry. However, any suitable cross-sectionalgeometry for struts 502 is also contemplated. In some implementations,strut characteristics can be made to vary for different regions of thelattice. One use for such a procedure can be to obtain similar benefitsto the biased seed point distribution described above. In thisimplementation, the cross-sectional diameter of a particular strut canbe made to vary as a linear, non-linear, stepped, or any other functionof the shortest distance between a given point on the strut (e.g. thecenter point or an end point) and a point on the outer boundary. Thisdistance may define a scale factor that is multiplied by a minimumcross-sectional area to define the cross-sectional area of thatparticular strut. If the function increases with increasing distancefrom the outer boundary, the struts will gradually thicken from theouter boundary to the inner boundary of the lattice, producing adecreasing porosity from the outer surface inward.

By utilizing the above-described process, an implant, for examplepatellar implant 102, having a large volume porous lattice model for animplant can be created with a single step of strut and node definition.Prior tessellation methods have required additional computation foraligning and joining individually tessellated sub-volumes of a largeroverall desired volume for the porous lattice. Thus, suchabove-described processes may eliminate steps of joining multiple tilesor multiple subdivided volumes of separately generated lattices or ofresolving redundant features therein, providing a more efficient designand/or fabrication process. In addition, the process of trimming theouter surface of the volume after creating a larger volume of lattice isan efficient way of generating open-ended struts that extend outwardfrom the overall surface of the lattice at a variety of angles,including struts that extend normal or near normal to the overallsurface of the lattice.

The above-described CAD modeling and fabrication process(es) can beperformed utilizing a computing device 1100, as described in connectionwith FIG. 10 below, and/or a fabricating device 1200, as described inconnection with FIG. 11 below. While computing device 1100 andfabricating device 1200 are illustrated and described as separatedevices, the present disclosure is not so limited and computing device1100 and fabricating device 1200 may be disposed within the same device.

FIG. 10 illustrates a computing device 1100 configured to generate a CADmodel of an implant comprising a porous lattice, according to someembodiments. Computing device 1100 can comprise storage 1130, which cancomprise computer memory configured to store one or more CAD programs,for example Element by nTopology of New York, N.Y. and/or AutodeskWithin Medical by Autodesk of San Rafael, Calif. Storage 1130 may alsobe configured to store a CAD model of an implant as previously describedin connection with any of FIGS. 1-9 .

Computing device 1100 can further comprise a processor 1120 configuredto perform one or more operations to thereby generate a CAD model of animplant as previously described, based on non-transitory,computer-readable instructions held within storage 1130.

Computing device 1100 can further comprise a graphical user interface(GUI) 1110, which can include a display 1112 configured to display theCAD model to a designer and/or user. Computing device 1100 can furthercomprise an input/output 1140 configured to accept user input and outputCAD files for the models created with the principles set forth above. Insome embodiments, input/output 1140 may be incorporated within GUI 1110,although the present disclosure is not so limited.

FIG. 11 illustrates a fabricating device 1200 configured to fabricate animplant device comprising a porous lattice based on at least one CADmodel, according to some embodiments. In some embodiments, fabricatingdevice 1200 can utilize additive manufacturing (AM) techniques, such asdirect metal laser sintering (DMLS), which selectively exposes layers offusible material, e.g., titanium or a titanium alloy, to a heatingsource, e.g., a laser. Such techniques are well known, for example asdescribed by Abe, et al., “Manufacturing of Titanium Parts for MedicalPurposes by Selective Laser Melting,” Proceedings of The EighthInternational Conference on Rapid Prototyping (Jun. 12-13, 2000)288-293, which is hereby incorporated by reference in its entirety.

In addition and/or alternative to any or all features described in Abe,et al., fabricating device 1200 can include storage 1230, which cancomprise computer memory configured to store one or more CAD models foruse in fabricating an implant device comprising a porous lattice as wellas one or more computer programs configured to control the laser andother operations of the fabricating device to fabricate the implantdevice comprising the porous lattice, based on the one or more CADmodels as previously described in connection with any of FIGS. 1-9 .

Fabricating device 1200 can further comprise a processor 1220 configuredto perform one or more operations for fabricating the implant based onthe one or more CAD models as previously described, based onnon-transitory, computer-readable instructions held within storage 1230.

Fabricating device 1200 can further comprise a graphical user interface(GUI) 1210, which can include a display 1212 configured to displayinformation related to the fabrication process to a user. Fabricatingdevice 1200 can further comprise a peripheral input device 1240configured to accept user input. In some embodiments, peripheral inputdevice 1240 may be incorporated within GUI 1210, although the presentdisclosure is not so limited.

Fabricating device 1200 can further include a fabricating apparatus1250, which may comprise any and all equipment for performing the DMLSAM techniques, at least as described by Abe, et al.

FIG. 12 illustrates a flowchart 1300 of a method for fabricating animplant device comprising a porous lattice, according to someembodiments. Flowchart 1300 may be performed in whole or in part byeither or both of computing device 1100 and fabricating device 1200 ofFIGS. 10 and 11 , as previously described in connection with any ofFIGS. 1-11 .

At block 1302, flowchart 1300 includes creating, by a computing device,a model of the implant device comprising the porous lattice. Forexample, computing device 1100 of FIG. 10 may be configured to create aCAD model of patellar implant 102 comprising porous lattice 114. Porouslattice 114 may comprise a Gaussian distribution of pore diameters of adesired width at half-maximum that is centered around a desired meanpore diameter. Patellar implant 102 comprises at least one post 112a-112 c configured to anchor bone of a patient to patellar implant 102.As previously described, the creating process of block 1302 may compriseone or more steps, blocks and/or processes as described by one or moreof blocks 1304 to 1320 below.

At block 1304, flowchart 1300 includes defining an initial latticevolume having a bounding surface for the implant device. For example,processor 1120 of computing device 1100 may be configured to defineinitial lattice volume 402 having a bounding surface for patellarimplant 102.

At block 1306, flowchart 1300 includes populating the initial latticevolume with a plurality of seed points. For example, processor 1120 ofcomputing device 1100 may be configured to populate initial latticevolume 402 with a plurality of seed points. A distribution of the seedpoints can be pseudo-random, for example based on a Poisson-discsampling strategy as previously described.

At block 1308, flowchart 1300 includes populating the initial latticevolume with a plurality of nodes and struts that connect the nodes todivide the initial lattice volume into a plurality of 3-dimensionalregions, thereby defining an initial lattice. Each 3-dimensional regionencloses a respective seed point of the plurality of seed points. Forexample, processor 1120 of computing device 1100 may be configured topopulate initial lattice volume 402 and with a plurality of nodes 504and struts 502 that connect the nodes to divide initial lattice volume402 into a plurality of 3-dimensional regions and thereby define initiallattice 500. As illustrated, each strut 502 can connect two nodes 504.This block may be carried out utilizing Voronoi tessellation aspreviously described.

At block 1310, flowchart 1300 includes defining a second volume withinthe initial lattice volume such that a trimming boundary is definedbetween the initial lattice volume and the second volume. For example,processor 1120 of computing device 1100 may be configured to define asecond volume within initial lattice volume 402 such that a trimmingboundary is defined between initial lattice volume 402 and the secondvolume.

At block 1312, flowchart 1300 includes removing from the model strutsand nodes located outside the trimming boundary. For example, processor1120 of computing device 1100 may be configured to removed struts andnodes located within initial lattice volume 402 but not within thesecond volume. This node and strut removal converts initial lattice 500to trimmed lattice 702, which excludes at least portions of struts 502outside the trimming boundary.

At block 1314, flowchart 1300 includes attracting one or more nodesand/or struts toward a substrate of the implant device such that atleast one node or strut is positioned coincident with or at least partlywithin the substrate of the implant device. For example, processor 1120of computing device 1100 may be configured to attract one or more nodesand/or struts toward a substrate of patellar implant 102 such that atleast one node or strut is positioned coincident with or at least partlywithin the substrate of patellar implant 102.

At block 1316, flowchart 1300 includes merging some or all of theattracted nodes and/or struts with the substrate of the implant device.For example, processor 1120 of computing device 1100 may be configuredto merge some or all of the attracted nodes 504 and/or struts 502 withthe substrate of patellar implant 102.

At block 1318, flowchart 1300 includes adjusting at least some of theplurality of struts to have a desired thickness and a desiredcross-sectional geometry. For example, processor 1120 of computingdevice 1100 may be configured to thicken at least some of struts 502 tohave a desired thickness and/or a desired cross-sectional geometry,e.g., a substantially circular geometry.

At block 1320, flowchart 1300 includes fabricating the implant devicecomprising the porous lattice at least in part by exposing fusiblematerial to a heating source according to the model. For example,processor 1220 may be configured to direct fabricating apparatus 1250 offabricating device 1200 (FIG. 11 ) to fabricate patellar implant 102comprising porous lattice 114 at least in part by exposing fusiblematerial, e.g., titanium or a titanium alloy, to a heating source, e.g.,a laser, according to the CAD model.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

What is claimed is:
 1. A method for fabricating an implant devicecomprising a porous lattice, the method comprising: creating, by acomputing device, a model of the implant device comprising the porouslattice, the creating comprising: defining an initial lattice volumehaving a bounding surface for the implant device, populating the initiallattice volume with a plurality of seed points, populating the initiallattice volume with a plurality of nodes and struts that divide theinitial lattice volume into a plurality of 3-dimensional regions,thereby defining an initial lattice, defining a second volume within theinitial lattice volume such that a trimming boundary is defined betweenthe initial lattice volume and the second volume, removing struts andnodes, and portions thereof from the model that are located outside thetrimming boundary to thereby generate free strut ends at a boundary ofthe second volume, and fabricating the implant device comprising theporous lattice at least in part by exposing fusible material to aheating source according to the model.
 2. The method of claim 1,comprising: attracting one or more nodes and/or struts toward asubstrate of the implant device such that at least one attracted node orstrut is positioned coincident with or at least partly within thesubstrate of the implant device, and merging some or all of theattracted nodes and/or struts with the substrate of the implant device.3. The method of claim 1, wherein a distribution of the plurality ofseed points is at least partially random or pseudo-random.
 4. The methodof claim 1, wherein the distribution of seed points has a higher densityin some regions of the lattice than others.
 5. The method of claim 1,wherein a distribution of the plurality of seed points is based at leastin part on a Poisson-disc sampling strategy.
 6. The method of claim 1,wherein all locations within each 3-dimensional region are closer to therespective seed point than to any other seed point.
 7. The method ofclaim 1, wherein merging at least the second node and at least theportions of any associated struts with the substrate integrates at leastthe portions of the associated struts with edge features of thesubstrate of the implant device.
 8. The method of claim 1, whereincreating the model of the implant device further comprises adjusting atleast some of the plurality of struts to have a desired thickness and adesired cross-sectional geometry.
 9. The method of claim 8, wherein theadjusting varies in different regions of the lattice.
 10. The method ofclaim 9, wherein the adjusting is different at different distances froman outer surface of the lattice.
 11. The method of claim 8, wherein thedesired cross-sectional geometry is a substantially circular geometry.12. The method of claim 1, wherein the porous lattice comprises aGaussian distribution of pore diameters centered around a desired meanpore diameter in at least one region of the lattice.
 13. The method ofclaim 1, wherein the implant device comprises at least one postconfigured to anchor bone of a patient to the implant device.
 14. Themethod of claim 1, wherein the implant device comprises a patellarimplant.
 15. The method of claim 1, wherein the fusible materialcomprises titanium or a titanium alloy.
 16. The method of claim 1,wherein the heating source comprises a laser.
 17. The method of claim 1comprising manipulating one or both of the free strut end position andfree strut orientation relative to the trimming boundary for at leastone of the free struts.
 18. A method for generating a fabrication modelfor an implant device comprising a porous lattice, the methodcomprising: creating, by a computing device, a model of the implantdevice comprising the porous lattice, the creating comprising: definingan initial lattice volume having a bounding surface for the implantdevice, populating the initial lattice volume with a plurality of seedpoints, populating the initial lattice volume with a plurality of nodesand struts that divide the initial lattice volume into a plurality of3-dimensional regions, thereby defining an initial lattice, defining asecond volume within the initial lattice volume such that a trimmingboundary is defined between the initial lattice volume and the secondvolume, and removing struts and nodes, and portions thereof from themodel that are located outside the trimming boundary to thereby generatefree strut ends at a boundary of the second volume.